1. Field of the Invention
The present invention relates generally to methods and systems for generating a dehydrated inert gas stream, and more particularly, but not by way of limitation, to inert gases particularly suitable for venting storage tanks and the like.
2. Description of the Prior Art
In the storage and transport of inflammable cryogenic fluids, such as liquefied natural gas, it is mandatory that storage tanks after containing such liquefied cryogenic fluids be purged with inert gas to prevent an explosive mixture of air and the inflammable fluid from occurring within the storage tank. Since liquefied cryogenic fluids must be refrigerated at very low temperatures, the inert gas used to purge the storage tanks must be dehydrated in order to prevent water from contaminating the cryogenic fluid and ice from forming on the walls of the tank. In the case of liquefied natural gas, the inert purge gas must be dehydrated to a dew point in the order of -50.degree.F at atmospheric pressure.
Heretofore it has been necessary to utilize nitrogen or other commercially available dehydrated inert gas as purge gas which is relatively expensive, and where the storage tanks to be purged are located on sea going transport vessels, storage space for transporting the purge gas in a liquid state as well as vaporizing equipment are required.
By the present invention methods and systems for generating a dehydrated inert gas stream are provided, which methods and systems are particularly suitable for installation on sea going transport vessels thereby eliminating the space and expense associated with heretofore used purge gas installations.